1. Field of the Invention
The present invention pertains to a substance for creating an environmental barrier and, more particularly, to a formulation and method of use for a liquid applied membrane to construct a structural barrier system that seals structural openings such as doors and windows.
2. Description of the Related Art
Tremendous damage to buildings, both large and small, is caused by water leaking into rough openings and framing due to faulty window and door installations or leaky windows. Owners, builders, and insurance companies can face tremendous costs in the restoration and repair of this damage. Window and door installation failure can cause delays in construction, increased insurance premiums for builders and building owners, warranty liability for builders, and increased cost of home ownership for the general population.
Even when builders carefully follow detailed installation instructions and recognized trade organization procedures, these window and door installation methods can leave the openings susceptible to water intrusion. Frequently, installation procedures are difficult to follow with multiple steps and layers of products have been used in an attempt to keep the water out. Complex installation procedures are often difficult to follow, and increasing the complexity of the installation procedure has not reduced the incidence of water intrusion and damage.
In recent years there has been an increasing use of liquid applied flashing membranes in the construction industry, especially in the course of installing windows and doors. Window and door penetrations of the building envelope are prone to water and air intrusion, resulting in health risks, structural damage, and financial loss. In the past, metal flashings have been used for this purpose but have low performance rates due to metallic corrosion, fastener penetration, thermal transfer and difficulty of fabrication on site. Self-adhered, flexible flashing membranes, typically consisting of a polyethylene membrane weather side with an SBS rubberized asphalt compound as the adhesive side, have offered an alternative. These products were established in the industry as a quality concept, but the construction site environment, wet conditions, staining of other construction materials, and non-vapor-permeable characteristics have resulted in construction failures. Drawbacks to these materials include difficult application techniques, adhesive failure on moist substrates, lack of resistance to weather exposure, and narrow service temperature along with the inability to effectively integrate the through wall component with an existing water and air barrier system.
One recent attempt to overcome the problem of attempting to apply a waterproof membrane to a complex penetration in the building envelope has been the development of liquid applied membranes. This concept consists of applying by brush, roll, trowel, or spray a material to the exterior construction wall penetration openings and at the exterior side of the wall sheathing or other substrates a product that becomes by way of cross-linking, solvent evaporation, coalescence or other such means of cure, a continuous membrane capable of resisting air and water penetration. A common problem with many of these materials is the inherent need for solvents, be they water, petroleum distillates, or other volatile materials required to reach a viscosity needed for the application technique. The volatile material is expressed into the surrounding atmosphere resulting in odor, health and fire danger, pollution, and other complications, most notably, loss of volume in the membrane. This loss in volume as the material cures creates tension at the crucial membrane-substrate interface, increasing the potential for adhesive and cohesive failure. These systems do not typically allow a continuous air and water barrier to be achieved across the interface of the component and the wall opening.
The use of liquid applied flashing membranes in the construction of residential and commercial structures is known. Common drawbacks are shrinkage of membrane, weather resistance during construction schedule, limited water-ponding resistance, and long-term flexibility, as well as limited ability to integrate the through-wall component with the prepared opening.
There is therefore a need for a liquid applied flashing membrane that can be applied under adverse conditions to irregular, moist substrates, forming a film membrane that renders the building envelope penetration or opening water and air proof, meets air barrier association requirements for air transmission through membranes, is elastic and weather durable, and does not emit dangerous or flammable materials. Such film will not shrink or pull away from the substrate under violent weather conditions, and it must be capable of inspection after completion, The material must meet Volatile Organic Compound (VOC) requirements in all of North America, must cure rapidly enough to maintain construction schedule deadlines, must be weather resistant to allow for extended exposure to exterior elements, and must allow water vapor transmission so the substrate can dry if it contains water when material is applied. The material must also be able to incorporate other products needed to transition water from a leaky building component, such as a window or door, to the exterior drainage plane of the structure.